1. Field of Invention
This invention relates to a plasma processing technique for manufacturing semiconductor devices, and particularly to a quartz component employed in plasma processing apparatus. This invention also relates to a method for restoring the quartz component.
2. Description of Related Art
Plasma processes, such as dry etching, are widely employed in manufacturing semiconductor devices. For example, etching is generally performed using a reactive gas activated by plasma. In dry etching techniques, however, components within the chamber of a plasma processing apparatus are often damaged due to their exposure to the plasma. In particular, a dry etching apparatus for etching silicon oxide, which requires high-energy ions, presents a serious problem in that it damages the components.
The plasma chamber components are generally formed of materials, such as quartz, anodized aluminum, silicon, silicon carbide, carbon, a fluorine-polymer material, various kinds of ceramic materials, or the like. The selection of the material is made from the perspective of electric insulation, workability, impurity concentration, and the like. However, none of the aforementioned materials can completely eliminate the problem of plasma damage.
Accordingly, the components of a plasma processing apparatus that suffer plasma damage are treated as expendables and are managed on the basis of a predetermined duration of use. That is, the components that have reached the predetermined duration of use are replaced with new ones.
In the event that the user uses a plasma processing apparatus, including the chamber components, beyond their predetermined duration of use, the damaged components may create a problem of, for example, unstable plasma discharge.
The chamber components are designed to generate a suitable current path. When the plasma damages any of chamber components, new current paths are formed, leading to the problem that a desired plasma discharge cannot be sustained. Furthermore, the flow of reactive gas may be influenced due to the damage of the chamber components, and unwanted particles may be generated from the damaged components.
Usually, however, the plasma does not damage the entirety of a chamber component, but damages only a specific portion of the component. Accordingly, replacement of the entire chamber component leads to unnecessarily high costs, and to waste of resources.
Accordingly, an arrangement is proposed that divides a component in a plurality of parts. In particular, Japanese Unexamined Patent Application Publication No. 10-265977 proposes to divide the shield ring, which suffers from the most serious damage in the chamber components, into an inside component and an outside component. The inside component is located at a position where the inside component particularly suffers from particle adhesion and damage due to sputtering. By constructing the inside component with a material highly resistible to particle adhesion and sputtering, the lifetime and hence the cycle of replacement of the shield ring is extended.
However, dividing a single component into multiple sub-components increases the number of chamber components, and leads to a problem of increased management costs.